[PATCH v5 0/7] consolidate and cleanup CPU capacity

From: Vincent Guittot
Date: Sat Nov 04 2023 - 06:59:18 EST


This is the 1st part of consolidating how the max compute capacity is
used in the scheduler and how we calculate the frequency for a level of
utilization.

Fix some unconsistancy when computing frequency for an utilization. There
can be a mismatch between energy model and schedutil.

Next step will be to make a difference between the original
max compute capacity of a CPU and what is currently available when
there is a capping applying forever (i.e. seconds or more).

Changes since v4:
- Capitalize the verb in subject
- Remove usless parentheses in cppc_get_dmi_max_khz()
- Use freq_ref pattern everywhere
- Fix MHz / kHz units conversion for cppc_cpufreq
- Move default definition of arch_scale_freq_ref() in
include/linux/sched/topology.h beside arch_scale_cpu_capacity
which faces similar default declaration behavior. This location covers
all cases with arch and CONFIG_* which was not the case with previous
attempts.

Changes since v3:
- Split patch 5 cpufreq/cppc
- Fix topology_init_cpu_capacity_cppc()
- Fix init if AMU ratio
- Added some tags

Changes since v2:
- Remove the 1st patch which has been queued in tip
- Rework how to initialize the reference frequency for cppc_cpufreq and
change topology_init_cpu_capacity_cppc() to also set capacity_ref_freq
- Add a RFC to convert AMU to use arch_scale_freq_ref and move the config
of the AMU ratio to be done when intializing cpu capacity and
capacity_ref_freq
- Added some tags

Changes since v1:
- Fix typos
- Added changes in cpufreq to use arch_scale_freq_ref() when calling
arch_set_freq_scale (patch 3).
- arch_scale_freq_ref() is always defined and returns 0 (as proposed
by Ionela) when not defined by the arch. This simplifies the code with
the addition of patch 3.
- Simplify Energy Model which always uses arch_scale_freq_ref(). The
latter returns 0 when not defined by arch instead of last item of the
perf domain. This is not a problem because the function is only defined
for compilation purpose in this case and we don't care about the
returned value. (patch 5)
- Added changes in cppc cpufreq to set capacity_ref_freq (patch 6)
- Added reviewed tag for patch 1 which got a minor change but not for
others as I did some changes which could make previous reviewed tag
no more relevant.

Vincent Guittot (7):
topology: Add a new arch_scale_freq_reference
cpufreq: Use the fixed and coherent frequency for scaling capacity
cpufreq/schedutil: Use a fixed reference frequency
energy_model: Use a fixed reference frequency
cpufreq/cppc: Move and rename cppc_cpufreq_{perf_to_khz|khz_to_perf}
cpufreq/cppc: Set the frequency used for computing the capacity
arm64/amu: Use capacity_ref_freq to set AMU ratio

arch/arm/include/asm/topology.h | 1 +
arch/arm64/include/asm/topology.h | 1 +
arch/arm64/kernel/topology.c | 26 +++---
arch/riscv/include/asm/topology.h | 1 +
drivers/acpi/cppc_acpi.c | 104 ++++++++++++++++++++++
drivers/base/arch_topology.c | 56 ++++++++----
drivers/cpufreq/cppc_cpufreq.c | 139 ++++--------------------------
drivers/cpufreq/cpufreq.c | 4 +-
include/acpi/cppc_acpi.h | 2 +
include/linux/arch_topology.h | 8 ++
include/linux/cpufreq.h | 1 +
include/linux/energy_model.h | 6 +-
include/linux/sched/topology.h | 8 ++
kernel/sched/cpufreq_schedutil.c | 26 +++++-
14 files changed, 225 insertions(+), 158 deletions(-)

--
2.34.1